This present invention relates to an imaging device such as a copying machine, more particularly to an imaging device, in which a photo and pressure sensitive recording medium (for example, photo and pressure sensitive micro-capsule sheet) on which a latent image has been formed in accordance with a visible image is overlapped with a color development medium (for example, color development sheet), for pressuring them, and forming a visible image on the color development medium side, capable of controlling a timing of pressurizing them in such a manner that these sheets are accurately overlapped.
As a prior art of this type of imaging device, as shown in FIG. 1, the following structure has been well-known. As a wound state photo sensitive micro-capsule sheet 37 is pulled, a latent image corresponding to a visible image of an original document is formed at an exposure stage 19. After that, a cut sheet type color development sheet 38 is contacted with the exposed side of the micro-capsule sheet 37 and then they are pressurized and developed by pressure development member, for example, a pair of pressure-developing rollers 21, 31, provided on a pressure development unit 20, thereby forming a visible image on the color development medium.
A plurarity of development sheets 38 are stacked in a casette case 32 and fed out by a semicircular roller 33, and further fed by a feed roller 34 to the pressure development unit 20 through a gate 35 one sheet by one sheet.
In this structure, the pair of rollers 21, 31 are normally open to prevent the roller surfaces from being dirtied by accidental pressuring of the micro-capsule sheet 37. The color development sheet 38 is fed synchronously at the feed speed of the micro-capsule sheet 37 and they are pressurized and developed by the close operation of both of the pair of rollers 21, 31.
In the above device, which further provides a function which increases or decreases the exposure amount on the micro-capsule sheet 37 or a function which enlarges or reduces a visible image by a copy scale factor, a structure where the feed speed of the micro-capsule sheet 37 is varied has been widely used. In this case, the nip timing of the pair of rollers 21, 31 is not changed, whereby a deviation occurs at the start pressure time. Thus, when the pressure operation starts before the color development sheet 38 is sent to the pair of rollers 21, 31, only the micro-capsule sheet 37 is pressurized and the surfaces of the pair of roller 21, 31 are dirtied by a crushing of a plurality of unhardened microcapsules coated on the surface of the micro-capsule sheet 37. On the other hand, when the pressure operation starts in the condition that the color development sheet 38 is excessively fed, the leading end of the color development sheet 38 is not developed.
In the enlargement or reduction state, the exposure start position of the micro-capsule sheet 37 is changed. In this case, the contact position of the exposure side of the micro-capsule sheet 37 and the color development sheet 38 deviates from the correct position.